(I have a job in which I am paired with a colleague and sent to various neighborhoods around town. If our assignments are close enough to the office, we walk. For a while, I am paired with a guy who is nice enough but has a few odd personality quirks. Sometimes, the only way for me to avoid getting mad at him is to play some harmless practical jokes. We are walking back to the office one evening after an assignment that went longer than expected. It is dark, and the street we are on is mostly deserted.)

Colleague: “I’m going to walk with my eyes closed!”

Me: “Why?”

Colleague: “Just for fun.”

(He mostly closes his eyes, but I can tell he is keeping one open just a tiny bit.)

Me: “Hey, watch out for that big rock!”

Colleague: “What? Where?”

(He opens his eyes and looks around, almost falling over while trying to avoid tripping over a rock that isn’t there.)

Colleague: “Hey! There’s no rock! You tricked me!”

Me: “Well, maybe you shouldn’t walk with your eyes closed, then.”

Colleague: “Hmph!”

(He closes his eyes again. I wait a minute or two.)

Me: “Oh, look! A dollar on the sidewalk!”

Colleague: “It’s mine!”

(He darts forward a few steps, searching the ground. When he realizes there is no dollar, he glares at me. I laughs.)

Colleague: “Jerk.”

Me:*laughing*

(And he closes his eyes again!)

Colleague: “I’m not going to let you trick me again. I don’t care what you say; I’m not falling for it.”

(I try warning him about another nonexistent rock, but it doesn’t work. He gets a smug look on his face. I get another idea.)

Me: “Good evening, ma’am. Lovely time for a walk, isn’t it?”

(My colleague opens his eyes and looks around, trying to figure out who I am talking to. There is nobody on the sidewalk except us, but until I burst out laughing, he is convinced that I am talking to someone.)